Extended Forecast Discussion NWS Weather Prediction Center College Park MD 201 PM EST Sun Jan 29 2023 Valid 12Z Wed Feb 01 2023 - 12Z Sun Feb 05 2023 ...Notable precipitation likely for the latter half of the week including heavy rain in the south-central to southeastern U.S. with freezing rain/snow on the northern side... ...Dangerously cold temperatures and wind chills are forecast across the Northern Plains/Upper Midwest and into the Northeast at times through the week... ...Overview... Guidance has been overall consistent with depiction of an overall flow pattern that offers periods of troughing are likely through much of the northern U.S. this week extending from a persistent Hudson Bay closed low, leading to colder than average temperatures for much of the northern tier. The cold temperatures and wind chills could be most hazardous for the north-central U.S. through around Friday, with significant cold extending into the Northeast by late week. Meanwhile a ridge/upper high over Cuba during much of the week should keep the Southeast warmer than normal. Between these upper-level features and temperature regimes, expect active weather as a southern stream upper trough/low ejects from the Southwest and tracks across the central/southern tier of the CONUS. This combined with a couple wavy fronts along with periods of Gulf inflow will support a couple of significant precipitation events with heavy rain and possible flooding to the south/southeast and wintry weather in the colder air. Later in the week, the West Coast may see increasing precipitation chances with the approach of an eastern Pacific upper troughing to potentially include an amplified upper low/trough and deepened surface system approach over next weekend to monitor. ...Guidance/Predictability Assessment... The WPC medium range product suite was primarily derived from a composite blend of reasonably clustered pattern evolution guidance from the 06 UTC GFS/GEFS, the 00 UTC ECMWF/UKMET/Canadian and the ECMWF ensemble mean through medium range time scales in a pattern with overall above normal predictability and decent ensemble, WPC continuity and National Blend of Models support. Despite overall flow similarities, the broad composite was used to mitigate, consistent with uncertainty, ample flow embedded shortwave timing and focus differences that grow over time. A composite of latest 12 UTC models and ensembles remains in line with this forecast strategy and maintains good WPC product continuity. ...Weather/Hazard Highlights... The southern stream upper trough/low tracking across the southern U.S. and the broader northern stream trough will provide support for frontal boundaries with waves of low pressure through the south-central to southeastern U.S., which combined with Gulf moisture streaming in will lead to widespread precipitation. On the southern side locally heavy rain is expected, which could cause localized flooding especially at times when there is sufficient instability for higher rain rates. At this time Slight Risks are in place in WPC's experimental Excessive Rainfall Outlook for both Wednesday from eastern Texas into the Lower Mississippi Valley and day 5/Thursday stretching into the Southeast given good upper-level support, namely excellent difluence/divergence in the right entrance region of the jet, as it tracks eastward. Then on the northern side of the precipitation chances, there is potential for snow across parts of the southern half of the Plains and Mississippi Valley into the Ohio/Tennessee Valleys and the Mid-Atlantic at times, but low confidence continues in the specifics, even with modest amounts. This is also a pattern that could support freezing rain with ice accumulations with the cold air in place at the surface and potential for warm moist air to flow overtop it. The placement of heaviest rain, freezing rain, and snow all remain in question as small-scale details like surface frontal positions and late week shortwave specifics remain uncertain. Drier conditions are likely for the East by Saturday. Elsewhere, periods of lake effect snow are possible to the lee of the northern/eastern Great Lakes. The West Coast could see increasing precipitation chances by later in the week but with uncertainty over the southward extent and amounts. Currently the best potential for at least some rain/mountain snow is over the Pacific Northwest with moisture possibly extending as far south as northern California, and as far east as the northern Rockies. Very cold conditions over the north-central U.S. during the short range period could continue into the latter part of the week, underneath instances of cold upper troughing. Guidance has fluctuated with the full extent of the cold intrusion, but the overall signal is strong. Highs in the single digits or even below zero are possible in the Dakotas into Minnesota while bitterly cold lows combined with wind will produce dangerous wind chills. Much below normal temperatures then shift into the Northeast by late week, with the possibility of highs below zero in northern New England by Saturday. Some record values are possible over the Northeast. Temperatures are expected to be generally below normal across much of the Interior West and central U.S. around midweek with gradual moderation thereafter. Meanwhile the far Southeast and Florida Peninsula should see the most consistent above average temperatures, with highs 10-15F above average and plus 10-20F anomalies for lows before a cooler trend next weekend. Tate/Schichtel Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation, experimental excessive rainfall outlook, winter weather outlook probabilities and heat indices are at: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml